On paper, I don't think Game packs are any better of a deal than Expansion packs are. They might even be a bit worse in terms of value for content.
What makes them feel like a better deal is the fact that the content is more centralized. As in you are less likely to end up paying for features which don't interest you, and also less likely to buy the pack if the main theme of it doesn't interest you at all.
Just as a simple example that I've used before- look at GTW. Get To Work includes active careers, retail stores, and aliens. These are three very different concepts that are all part of the same pack. Even if someone only wanted one or two of these features, they are paying for all three whether they like it or not. And ignoring any of these features devalues that pack for that person.
It's harder to fall into that kind of trap with a game pack because the content is usually all centered around one theme and one theme only. Those who are interested in that theme will buy it and get good use out of the pack. Those who are not interested will probably skip the pack entirely and keep their money in their pocket (with the exception of those who will buy a pack for BB/CAS only, but this betrays the concept of buying something for value anyway.)
The main problem with TS4 EP's is not that they don't put enough content in them, it's the strange decisions they make into what that content is. Like creating an entire system to allow us to paint galaxies and meadows onto our cats and dogs whilst neglecting to add practically any actual gameplay for them. Or taking a pack about going to work which only has three new work opportunities and a tiny world, and throwing in aliens and an alien planet. This type of poor resource allocation is what really makes these packs feel like a bad deal (just in my opinion, I'll be clear that I'm not trying to speak for anyone else here.)
